Anchor



March 20, 1956 E. R. VORENKAMP 2,738,750

ANCHOR Filed Oct. 18, 1954 I 2 Sheets-Sheet 1 FIG.9

INVENTOR E.R. VORENKAMP HIS AGENT March 1956 E. R. VORENKAMP 2,738,750

ANCHOR Filed on. 18, 1954 2 Sheets-Sheet 2 INVENTOR:

ER. VORENKAMP HIS AGENT United States Patent() ANCHOR Egbert R. Vorenkamp, New Orleans, La., assignor to Shell Development Company, New York, N. Y., a corpora- This invention relates to anchors and pertains more particularly to ship or barge anchors adapted to be readily worked in mud to securely anchor a drilling rig barge or other type of vessel on mud flats such, for example, as those commonly encountered along the coast of Texas and Louisiana.

The anchor of the present invention is related to and is an improvement on the anchor described and claimed in co-pending patent application Serial No. 354,567, filed May 12, 1953 now Patent 2,721,530 dated October 25, 1955.

The present anchor is applicable for use with any type of ship vessel or barge where an anchor with high-holding power is desired for use in soft, unconsolidated soil conditions on the sea floor. Anchors of high-holding power are required to insure immobility of drilling tenders while on or near drilling locations, to obtain controlled move-r ment to or from these locations and to protect all types of vessels, ships, etc., during hurricanes, typhoons and/or other adverse conditions in or near inland waters bordering the Gulf of Mexico. The principal disadvantage of the anchors-now in use is that they depend partially on the weight to obtain high-holding power. Additionally, the fiukes of the anchors presently used, are not designed or arranged so as to cause deep penetration in a soft, muddy sea bottom, and the area of bearing surface is insufficient to develop high-holding power in soft soil conditions. Further more, their design is such that they are not inherently stable during burial.

It is, therefore, a primary object of the present invention to provide a anchor having high-holding power in very soft soil conditions.

A further object of this invention is to provide a light weight anchor which is inherently stable during burial insoft, muddy sea bottoms. i

Another object of this invention is to provide a lightweight anchor which may be readily pulled into or from deep penetration depths in a soft, unconsolidated sea floor.

\ Another objectof this invention is to provide a lightweight anchor adapted to be sunk deep in the mud without the addition of excess weight during the sinking operation.

These and other objects of this invention will be understood from the following description taken with reference to the drawing, where:

Figure 1 is an isometric view of the present anchor attached to a cable by which it may be connected to a vessel.

Figures 2, 3 and 4 are plan, front and side views of the present anchor.

Figure 5 is a diagrammatic view illustrating a barge towing the present anchor and embedding it in the thick layer of soft, unconsolidated soil under a body of water.

Figures 6, 7 and 8 are views of different forms of anchor according to the invention.

Figure 9 is a fragmentary view of the main plate of the ICE anchor including a tooth and illustrating a modified form of support plate.

Referring to Figures 1, 2, 3 and 4 of the drawing, the present anchor comprises a main plate 11 having fixedly secured thereto as by welding a normally vertical 'supporting guide or stabilizing plate 12, and, if desired, one or more reinforcing normally horizontal members 13. If a single horizontal support plate 13 is employed, it is preferably secured across the main plate 11 near the bottom thereof, or, in other words, parallel to that edge of the substantially triangular main plate which serves as the base of the anchor. While the horizontal support member 13 is shown as an angle-iron (Fig. 4), a flat supporting member 13 may be. employed instead in order to reduce the resistance of the anchor as it passes through mud and water.

The main plate 11 is preferably substantially triangular in shape although it may be of any desired regular or irregular shape, rectangular, oval or even round. Preferably, the bottom edge of the main plate is horizontal or flat so that it tends to cut into a sandy bottom or ocean floor.

The vertical supporting guide plate 12 which is also preferably substantially triangular in shape and is fixedly secured to the main plate 11, as by welding, so that it extends outwardly therefrom with the larger portion of the guide plate 12 secured opposite the base of the triangular main plate 11 in order to concentrate the weight near the bottom or base of the anchor. The vertical guide plate12 is preferably secured to the main plate 11 along a line extending from the apex or top 14 of the anchor initially contact the ocean floor.

to the mid-point in the base 15 of the anchor. If desired, a plurality of teeth 16 may be provided on the lower edge of the main plate 11 to insure initial penetration of the anchor. Additionally, in order to concentrate the major portion of the weight of the anchor in the lower half thereof, a portion of the lower half of the main plate 11 adjacent its base 15 may be made substantially thicker and heavier than the upper portion of the main plate, as illustrated in Figures 1 and 4 of the drawing. 7

The vertical guide plate 12 serves both as a rigid member by which the anchor may be towed and as a guide or rudder to insure that the main plate 11 drops through the water in a vertical plane so that its lower edge 15 or teeth 16 As a towing member the guide plate 12 is superior to a rigid or flexible bridle attached. at two or more points to the main plate in that the single guide plate offers less resistance to the unconsolidated material through which the anchor is to be drawn. The shape of the vertical guide plate 12 and the position in which his secured to the main plate 11 is such that the angle between the bottom edge of the guide plate 12 and the face of the main plate 11 forms an angle preferably between and degrees. The angle desired at this point depends upon the type of material or formationon the ocean floor into which the anchor is to be drawn.

The bottom edge of the guide plate 12 may extend outwardly in a horizontal line away from the bottom of the main plate 11 or may slope downwardly away from the bottom of the main plate to provide suflicient area in the outwardly-extending end of the guide plate 12, below the center of lateral resistance of the main plate 11, for

drilling therein a plurality of holes 17 by which a cable 18 (Figure 1) may be secured to the anchor. It is essential that the anchor cable be secured to the anchor at a point below its center of lateral resistance when the anchor is being pulled through mud or unconsolidated material, so that the main plate of the anchor forms an angle of from ,95 to degrees with the anchor cable to which it is secured, thereby causing the anchor to penetrate the ocean floor at the desired angle (preferably, about 25 degrecsfrom the vertical). Theprovision of multiple vertically-spaced holes 17 in the outwardly-extending end of the guide plate 12 permits a quick change in the penetration angle of the anchor by afiixing the anchor cable.

to a higher or lower hole. Instead of employing holes 17. inguide plate 12'for attaching the cable thereto, other suitable types of cable connector means may be used such as a. clevis, or a series of eye-bolts or chain swivels.

The principle of operation of the present anchor may be readily understood. by reference to Figure 5 of the drawing. When a force is exerted by a cable on a plate 11 through its guide or towing plate 12, the plate rotates about the end of the cable, due to the resisting forces of the surrounding medium, to a position such as shown at Y in Figure 5 where the acting force passes through the center of gravity of plate 11. Since the major resisting force acts perpendicularly to the plane of the plate, a vertical component of this force is exerted on the plate. If the plate 11- is in a medium of substantially uniform fluid, the plate will move through an angle from a position X. to a position Y asshown in Figure 5.

Considering position Y of Figure for example as the general case of angles of 0 between 0 and 90 and analyzing the forces, it can be seen that the anchor will penetrate into very soft soil conditions (comparable to a fluid medium) on the sea bottom. The actual depth of penetration is a function of the magnitude of force on the anchor line, the length of the anchor line, and the resistance of soil. in the sea bottom. In operation, as illustrated in Figure 5, the anchor 11 is immersed in a body of water at any desired distance from a barge 27, the anchor line 18 being secured to the barge in any suitable manner, for example, by means of a winch (not shown). The kite-shaped anchor 11, which is preferably made of plate steel, together with its guide plate 12 offers only a minimum of resistance as it sinks edgewise and buries itself deep into the soft, unconsolidated soil on the sea floor. Any force applied to the anchor line 13 pulls the anchor 11 more deeply into the soft soil. Because of the large bearing area of the main plate 11, high-holding power is obtained even in very soft soil since the anchor penetrates down through the very soft soil to firmer soil. As the anchor line pull increases, the developed .holding power also increases. It is to be noted that the supporting vertical guide plate 12 provides a stabilizing action and guides the anchor 11 during burial in the direction of the pull in addition to reinforcing the main plate.

In off-shore drilling operations the present anchor may be used to secure a portable drilling rig barge on its location and thereafter may be employed to supply the required pull in. moving the barge to another drilling location. One of the problems commonly encountered in off-shore drilling operations in the Gulf of Mexico is that of moving a barge-mounted drilling rig a distance of several miles over a bottom consisting of mud when the draft of the rig barge is one foot greater than the apparent depth of the. water. This moving is usually effected by dropping the anchor at some distance ahead of the barge, pulling up the barge to the anchor, raising the anchor and dropping it further ahead of the barge, and repeating the operation. This requires, however, a firm grip of the anchor on the ground, which conventional anchors often fail to give. For example, during off-shore operations in the Gulf of Mexico, a 2850 lb. Danforth anchor offered no resistance at all in the soft mud encountered, at one particular location. Another anchor weighing 5 tons was readily moved through the soft clay with a pull of only tons which was by no means sufficient to budge a drilling barge. However, the barge could be easily moved by employing an anchor according to the present design as described above, which only weighed 650 lbs. and withstood a pull of 70 tons because it had dug itself to a depth of 46 feet .into the soft mud.

The. use of. a guide or towing plate 12 allows theanchor to penetrate deep into the soft sea bottom as the line pull on the anchor line is increased, while the barge bearing surface of the anchor gives it high-holding power in very soft soil conditions. The holding power referred to herein is the ratio of the developed holding power to the weight of the anchor.

At another time during off-shore operations it was desired to move a drilling barge weighing 4500 tons which had been sunk to the ocean fioor in 30 feet of water.

Two 2850 pound Danforth anchors were sunk totheoccan floor off the bow of the barge. When tension was applied to the cables attached to these anchors, the barge could not be moved, since the anchors gave way first. Subsequently, two 1000 pound anchors were fabricated in accordance with the construction of the present invention and sunk in the same positions. A 30,000 lb. pull by the barge winches on the anchor cable lines pulled the two kite-shaped anchors feet into the. mud on the ocean floor to firmly anchor them as the barge was readily moved from, its location.

When it is desired to move the anchor to. a new position, the anchor may be vertically withdrawn from the mud by a cable (not shown) which is attached to the retrieving cable hole .26 of the anchor 11 shown in Figure 4, the other end of the cable being attached to a float (not shown).

I claim as my invention:

1. An anchor of high-holding power in soft muddy sea bottoms, said anchor comprising a fiat main plate of substantial weight so that the anchor readily sinks to the bottom, rigid stabilizing plate means fixedly securedsaid stabilizing plate means at a point below the centerof lateral resistance of said main plate developed as the anchor is pulled through the water.

2. An anchor of high-holding power in soft muddy scafbottoms, said anchor comprising a fiat substantially triangular main plate of substantial weight so that the anchor readily sinks. to the bottom, rigid stabilizing plate means fixedly secured along one edge to said main platev on one side thereof and normal thereto, said stabilizing plate means extending outwardly from sm'd main plate and extending over an appreciable length of the main. plate from one side thereof, said side constituting the bottom of the anchor, the major portion of the weight of said main plate and stabilizing plate means being in the bottom half of said anchor, connector means carried by stabilizing plate means near the outwardly-extending edge thereof for securing. an anchor cable thereto, said connector means being carried on said stabilizing plate means at-a point below the center of lateral resistance of said main plate developed as the anchor is pulled through the'water.

3. An anchor of high-holding power in soft muddy sea bottoms, said anchor comprising a flat substantially triangular mainplate of substantial weight: so that the anchor readily sinks to the bottom, rigid stabilizing plate means fixedly secured along one edge to said main plate onone side thereof and normal thereto, said stabilizing plate means extending outwardly from said main plate, the bottom edge of said stabilizing plate means forming at least a '90 degree angle with the face of the main. plate, Said stabilizing plate means extending over an appreciable length of the main plate from one side thereof, said side constituting the bottom of the anchor, the major portion of the weight of said main plate and stabilizing plate means being in the bottom half of said anchor, connector means carried by stabilizing plate means near the outwardly-extending edge thereof for securing an anchor cable thereto, said connector means being carried on said stabilizing plate means at a point below the center of lateral resistance of said main plate developed as the anchor is pulled through the water.

4. An anchor of high-holding power in soft muddy sea bottoms, said anchor comprising a fiat substantially triangular main plate of substantial weight so that the anchor readily sinks to the bottom, rigid triangular-shaped stabilizing plate means fixedly secured along one edge to said main plate on one side thereof and normal thereto, said stabilizing plate means extending outwardly from said main plate, the bottom edge of said stabilizing plate means forming an angle of from 90 to 145 degrees with the face of the main plate, said stabilizing plate means extending over an appreciable length of the main plate from one side thereof, said side constituting the bottom of the anchor, the major portion of the weight of said main plate and stabilizing plate means being in the bottom half of said anchor, connector means carried by stabilizing plate means near the outwardly-extending edge thereof for securing an anchor cable thereto, said connector means being carried on said stabilizing plate means at a point below the center of lateral resistance of said main plate developed as the anchor is pulled through the water.

5. An anchor of high-holding power in soft muddy sea bottoms, said anchor comprising a flat substantially triangular main plate of substantial weight so that the anchor readily sinks to the bottom, rigid triangular-shaped stabilizing plate means fixedly secured along one edge to said main plate on one side thereof and normal thereto, said stabilizing plate means extending outwardly from said main plate, the bottom edge of said stabilizing plate means forming an angle of from 90 to 145 degrees with the face of the main plate, said stabilizing plate means extending over an appreciable length of the main plate from one side thereof, said side constituting the bottom of the anchor, the major portion of the weight of said main plate and stabilizing plate means being in the bottom half of said anchor, connector means carried by stabilizing plate means near the outwardly-extending edge thereof for securing an anchor cable thereto, said connector means com prising a plurality of holes drilled in a substantially vertical, line in a portion of said stabilizing plate means located at a point below the center of lateral resistance of said main plate developed as the anchor is pulled through the water, and means carried at the apex of said main plate for connecting a retrieving cable to said anchor.

References Cited in the file of this patent UNITED STATES PATENTS 902,075 Hamilton Oct. 27, 1908 1,016,998 Johanning et al Feb. 13, 1912 1,325,693 Deam Dec. 23, 1919 1,838,745 Croney Dec. 29, 1931 

